Ferulic Acid Esterase

Ferulic acid esterase (FAE) is a recently discovered enzyme with a very broad application range. Ferulic acid esters are formed in cell walls as ester linkages between hydroxy substituents of the xylan (carbohydrate) chain and acid residues from the ferulic acids. Additionally, the ferulic acid moieties may photodimerise, which further crosslinks the xylan chains and results in the carbohydrate components becoming inaccessible to enzymatic hydrolysis. In general, ferulic acid esterase is involved in hydrolysing recalcitrant parts of the plant cell wall, the beginning of a process that enables more complete breakdown of fibrous or pectinaceous cell walls and consequently the release of a higher proportion of sugars or cell wall bound flavours. The increase in the hydrolysis of the cell wall is brought about because the ferulic acid esterase breaks bonds that restrict accessibility of other cell wall hydrolases to their substrate. Consequently ferulic acid esterase gives improvements in any process where a more complete breakdown of the cell wall, or increase in the release of free sugars is an advantage.

The specific bond that is hydrolysed is the ester bond between a phenolic acid moiety and a sugar, which is linked to the xylose backbone of the cell wall, usually an arabinose residue (and sometimes a galactose residue). Hydrolysis, therefore, results in the production of a free phenolic acid, which may be used in the production of other commercially significant compounds such as p-coumaric acid, which is used as a photoactive ingredient in sunscreens, or a further biotransformation which will give rise to natural vanillin.

Fruit juice and vegetable processing also benefit from the inclusion of that.The resulting increased cell wall breakdown means that the filtration of the final product is much easier due to the reduction in particulate matter present.

Ferulic acid esterase  would benefit in carrot processing, whether the desired result is the complete liquifaction of the carrot, or the extraction of juice.

Flavour extraction may also be enhanced by Ferulic acid esterase because of the more complete hydrolysis of the cell wall that is attained. This enables more of the entrapped flavour components to be released in many extraction processes. Although processes vary considerably, this enzyme is active in the temperature range of 30 - 50¾C and at mildly acidic to neutral pH.

The other modified type of Ferulic acid esterase can benefits when used in brewing: more fermentable sugars can be released which means that the amount of substrate for the fermentation can be reduced.

Waste processing of natural products, eg. corn, wheat, sugar beet can be carried out using this enzyme, in conjunction with other cell wall hydrolases. In addition to the advantages of having less solid material to transport at the end of any processing that has the ability to release free phenolic acids from the waste material, which with a simple biotransformation can give rise to value added products such as p-coumaric acid a common protectant used in sun cream and vanillin